Imagine zipping from Paris to Tokyo in less than three hours, on a plane powered by all-natural ... seaweed. That's the premise of aircraft manufacturer EADS's Zero Emission Hyper Sonic Transport (ZEHST).

The ZEHST is something of a descendant of the famed Concorde line of aircraft, which brought to the mainstream supersonic flight -- air travel so fast that it could break the speed of sound. The Concorde flew its last in 2003. The next generation of supersonic aircraft aims to be even faster, and much more environmentally friendly.

The ZEHST aircraft, powered by biofuel made of seaweed, is due out in 2050. EADS didn't respond to our requests for comment, but CNN reported on the details when the ZEHST was first unveiled at the Paris Air Show in June 2011.

At the show, EADS said the plane's three engine types -- conventional jets, rockets and supersonic "ramjets" -- will allow it to speed at Mach 4, around 5,000 kmh. That would cut the flight from Paris to Tokyo to 2.5 hours, down from 11 hours. Perhaps a transcontinental commute is in reach. -Julianne Pepitone